1. Field of the Invention
The present invention relates to an information reader for emitting marker light to a display medium to light up an information code of the medium placed in a readable area of the reader and to position the reader over the medium such that the reader can optically read the information code by illuminating the information code of the medium with illumination light.
2. Description of Related Art
To record information on an article such as a commercial article or the like, an information code is marked in a code area of a display medium attached to the article. This information code is optically read out by an information reader. That is, the reader initially emits marker light having images of a plurality of guide markers. A user directs the reader toward the medium so as to light up the information code of the medium placed in a readable area of the reader using the marker light, and the user places the center of the marker light indicated by the guide markers at the center of the information code. Therefore, the reader is positioned over the medium such that an image of the information code can be appropriately formed in a light receiving system of the reader. That is, the reader is focused on the medium. Then, the reader emits illumination light to the medium, and the light reflected from the medium is received in the light receiving system. Therefore, the reader can optically read the information code of the medium.
This reader is, for example, disclosed in Published Japanese Patent First Publication No. 2006-330987. In this Publication, an information reader has a marker optical system and a light receiving optical system. A marker light source of the marker optical system emits marker light to an object (i.e., display medium) along an optical axis of the marker optical system to appropriately position the reader over the object. In the light receiving optical system, a light receiving axis of the optical system coincides with the optical axis of an image forming lens and intersects the surface of a light receiving sensor at right angles. The lens converges illumination light reflected from the object onto a surface of the sensor.
The optical systems are disposed such that the optical axis of the marker optical system and the light receiving axis of the light receiving optical system cross at an intersection at a small angle. The distance between the reader and the intersection is set to a reading distance appropriate to the reader. When a user places the reader over the object at the reading distance, an image of an information code marked on the object is formed on the surface of the sensor. Therefore, the reader can read the information code from the image. To arrange the optical systems having axes crossing each other in the reader, an optical element including the light source in the marker optical system is disposed on the upper side of the lens of the light receiving optical system so as to be inclined to the lower direction. In this structure, the optical element of the marker optical system is inevitably disposed in the reader to be inclined with respect to an optical element (i.e., sensor and lens) of the light receiving optical system.
However, to arrange the optical systems of the optical systems inclined each other such that the axes of the optical systems cross at a small angle, it is required to attach the optical elements to respective supporting members (e.g., printed wiring boards). Alternatively, when the optical elements are attached to the same supporting member, it is required that one of the optical elements is indirectly attached to the supporting member through a spacer or the like. Therefore, the number of parts and the number of assembling processes required for the reader are undesirably increased. Further, it is required to minutely adjust the orientation of at least one of the optical elements. Therefore, an adjusting process for the optical systems is inevitably required.